The aim of the current competing renewal proposal is to extend previous work conducted under the auspices of NS32976. The conceptual framework of the proposal is that the neural circuitry involved in processing faces becomes specialized as a result of experience viewing faces. A series of studies is proposed that examines how the timing, dose, and duration of different types of experience influence the development and neural bases of face processing. Particular attention will be directed toward the infant's and child's ability to recognize faces from unfamiliar species ("other-species effect"), unfamiliar races ("other race effect"), unfamiliar gender (e.g., infants reared disproportionately by mothers or by fathers), and unfamiliar ages (i.e., the ability to recognize faces of infants, children or elderly adults, co-varied against experience viewing such faces). The premise underlying these studies is that the perceptual window through which faces are viewed is broadly tuned at birth, and narrows with experience. To examine the developmental function of this perceptual narrowing, a training study will also be performed to ascertain whether the perceptual window can be kept open (or the sensitive period prevented from closing) by enriched experience. The specific questions to be addressed are: a) What is the developmental course of perceptual narrowing? b) Can the perceptual window be kept open with training? And c) How broadly tuned is the perceptual window? Across all studies, the primary means by which brain function will be inferred will be the recording of event-related potentials;various behavioral probes, appropriate to each age group, will also be employed. With regard to ERPs, particular attention will be paid to face-specific components and the spatial distribution of these components, from which inferences will be drawn about underlying neural sources.